160*s of BULL****...

[Backfire]

<blockquote>quote:</font><hr>Originally posted by Dominic

The quote "A cool engine draws heat out of the combustion process - less vapor (combustion) pressure, less ability to do work (push the piston down)." is also extreme . The actual FLAME TEMPERATURE is the same everyime the cyl ignites, and by having cooler heads and block you will have a slightly tighter cyl area and desner incoming air - which in turn creates higher cyl pressures (slightly) once fired. The idea is not to have the engine as hot as possible, but to have the largest delta temperature (change in temps) between the power stoke and intake stroke. <hr></blockquote>

As you pointed out earlier, there is little expansion in iron, so the "slightly tighter cyl area" should be insignificant as well.

The way you make power, is to convert as much energy from the combustion of the fuel to mechanical work as possible. Thermal efficiency is a measure of the actual work per cycle vs the energy released during combustion. The main loss of energy is through heat. Any heat in the exhaust after it exits the combustion chamber is wasted, unless you use a turbo to extract it. Any heat lost to the cylinder walls is wasted as well. That is why high cylinder wall temperatures can help improve thermal efficiency. The temperature difference between cylinder air and the walls determines the rate of heat loss to the cylinder walls through convection. By minimizing the difference, you slow heat transfer, and retaining the energy within the cylinder. By keeping the energy within the cylinder, more energy can be converted to mechanical energy (work done on the piston by the air), and the thermal efficiency improves.

And for what ever its worth, Nox formation is greatest near stoiciometric conditions and high combustion temps, not cooler. Also, the flame temperature is not the same as the cylinder temp. When you are looking at peak cylinder temperature and pressure, I don't believe it is the same as the flame front temp.

One thing to point out in this debate is that it is nearly impossible to make a "singular" statement on how changing one engine parameter will affect performance. The difficulty with engines is that one change will effect everything else, which inturn causes more changes. For example, the cooler cylinder wall temps will effect numerous things. The intake change will start cooler as it is compressed, this will change the combustion temperetures which will alter the burn characteristics. These will affect the completeness of the reaction, and the heat losses, etc, etc, etc. Very interesting discussion.

[ June 14, 2002: Message edited by: Backfire ]</p>

[Dekay]

This guy who told you this is a moron. It won't make you fail emissions. It just won't.

[Skullcamaro]

They guy from that garage doesn't know what he is talking about. For one thing, all the t-stat does is allow the coolant to begin to flow at a lower temp. The stock fan(s), etc still come on at the same time unless you have your PCM reprogrammed. It won't hurt your car and it would probably benefit especially in hotter climates. I've had mine in for quite a while without any problems and I have my car checked regularly by a professional mechanic and myself. I say go for it, if you don't like it, it is easy to change and it doesn't hurt your mpg either just so you know.

[Dominic]

<blockquote>quote:</font><hr>Originally posted by V6Bob:
1. At an 85mph cruise both thermostats are wide open. There is absolutely no difference between them.

2. To think that a thermostat would change mpg from 36 to 27 goes way beyond myth. It might make a 1 mpg difference, maybe (but I don't think so).

The most important thing about a 160 thermostat is that, if the day is cool, the engine is not fully warm, and/or the radiator/fans are set to give more cooling; the fuel injection will be fooled into running a bit richer. The next most important thing is that the temperature of the incoming mixture will be reduced a bit so it will be denser. Differences in "engine efficiency" will be small compared to these.

The most important drawback is that your oil may not heat up as much and may retain more contamination.

This is a mod that is not worth it on anything less than an all out drag car, IMHO. In a street car mostly what changes is the speed the car warms up and the differences are more in peoples heads.<hr></blockquote>

#1 is incorrect. The 160 thermostat was regulating my temperature at 166°F according to GM's Tech2 (I had a dealer check it for me during the trip since the radiator felt nice anc chilly)
, and the 195°stat kept my water temp at 195+ degrees.

At 85mph there is sufficient wind flowing through the radiator (or any highway speed for that matter) to properly cool the coolant to whatever the thermostat is set to, if the thermostat is working properly. If you run a 160 stat, and you run for hours on end down the highway, you will be running between 163 and 166 degrees, regardless of what your temp gauge reads!!!

Oil won't heatup properly... Also wrong. Install an oil temp gauge, then run a 195 thermo and a 160 thermo, you'll see the oil temp will remain between 210 and 240 degrees depending on what you're doing and whether or not you have an oil cooler on your fbody. This was proven on ls1 fbodies, and it holds true for V6s as well.

It is a worthless mod to those who think cooler running engines are worse. 160 degree water is not in any way cool, not even for an engine. Take your hand and stick it in a pot of 160 degree water, then come back and tell me its cold if you think thats cold.... you'll be handily burnt I'm sure!

Again I will restate the following, which I quote from a book entitled "Internal Combustion Engines" that was published by the U.S. Navy/AF for navy/AF mechanics.

It states "It has been found on all gasoline burning internal combustion engines that a water temperature between 145°F and 160°F is optimal for maxiumum horsepower and fuel efficiency. Running at higher water temperatures than 170°F reduces overall engine efficiency by 5-8% and is not recommended for any internal combustion engine."

Now, say what you want - but I'm finished. I'm sure a 180° stat in a modern engine is fine, but a 160° is only that much better IMO, and I think a 195° is ludicrois.

[ June 14, 2002: Message edited by: Dominic ]</p>

[Brett Garret]

*reads all posts.... walks slowly to bed....lays down and crys himself to sleep*

'To be or not to be THAT IS THE QUESTION'

[DominusEtDeusNatus]

1. Hot engine makes more power then a cold engine
2. Cold intake makes more power then a hot intake.

I could be totally wrong, but here it goes.

1. Lost heat is lost horsepower. All that heat going out the exhaust pipes and into coolant is lost. Usually about 60% of the fuels energy is converted to work. The remaining 40% is dissipated as heat. Imagine if you had 40% more power. That 200hp 225tq engine of yours would now have 333hp 375tq. And that drivetrain loss another 20% is taken from that 60% that does work. So only 20% of the 60% is actually accelerating the car. It's better to have a hotter engine up to the point of detonation. We get more timing with lower temperatures so lower temp thermo does help. But only because PCM adds timing. Program that timing into the PCM for higher temps and lower temp thermo won't do much.

2. Obviously colder air is denser then hotter air. This I don't have to explain.